Slicing a column into slabs and reuniting the slabs in a tapered portion of the extrusion die

ABSTRACT

Bolted to the auger barrel of a brick extruding machine is an internal tapering die base to which is clamped an internal tapering shaper cap whose cross section upstream of its mouth is provided with tensioned wires which slice the column longitudinally as it proceeds through said shaper cap. Downstream of the horizontal wires, the continued taper of the shaper cap forces into cohesion, by tremendous pressure, the adjacent longitudinal wire cut surfaces of the severally created adjacent slabs, sufficiently enough to permit each transversely cut section, of the resulting multi- sectioned extruded unit, to be safely man- or machine-handled and to be processed through its subsequent drying and firing cycles like normal full- size brick, units that can at any time after firing be tapped apart on the original wire cut lines to create brick slabs, each e.g., 3/8 &#34; to 1&#34; thick, which are especially economical and useful for facing the surfaces of industrialized mass-produced building panels of any practical size/

Nov. 20, 1973 P. s. KELSEY SLICING A COLUMN INTO SLABS AND REUNITING THESLABS IN A TAPERED PORTION OF THE EXTRUSION DIE 2 Sheets-Sheet 1 FiledMay 10, 1972 Nov. 20, 1973 P. s. KELSEY 3,773,880

SLICING A COLUMN INTO SLABS ANI) RHUNI'IINL: 'lllll Jib/H3}; IN I\TAPERED PORTION OF THE EXTRUSTON D1111 Filed May 10, 1972 2 Sheets-Sheetz United States Patent O US. Cl. 264-56 9 Claims ABSTRACT OF THEDISCLOSURE Bolted to the auger barrel of a brick extruding machine is aninternal tapering die base to which is clamped an internal taperingshaper cap whose cross section up stream of its mouth is provided withtensioned wires which slice the column longitudinally as it proceedsthrough said shaper cap. Downstream of the horizontal wires, thecontinued taper of the shaper cap forces into cohesion, by tremendouspressure, the adjacent longitudinal wire cut surfaces of the severallycreated adjacent slabs, sufficiently enough to permit each transverselycut section, of the resulting multi-sectioned extruded unit, to besafely manor machine-handled and to be processed through its subsequentdrying and firing cycles like normal full-size brick, units that can atany time after firing be tapped apart on the original wire cut lines tocreate brick slabs, each e.g., to 1'' thick, which are especiallyeconomical and useful for facing the surfaces of industrializedmass-produced building panels of any practical size.

This application is a continuation-in-part of application Ser. No.18,173, filed Mar. 10, 1970, now abandoned.

BACKGROUND OF THE INVENTION In recent years, especially in the UnitedStates, brick has been losing ground as a construction material becauseof the high cost of bricklayer labor, the sensitivity of bricklayingscheduling to weather conditions, the difficulty of and need forhandling individual bricks at a construction site, the relative slownesswith which a bricked building can be closed-in so that building interiorcon struction can be begun.

On the other hand, brick is an elegant building material, since itrequires so little maintenance over the building life and can constitutewalls of indisputably handsome appearance, among other advantages.

So it is considered well worth an intensive effort to keep this elegantbuilding material from suffering further deterioration of marketpenetration.

Most attempts at industrialized production of building panels includinga fully or partly embedded/ exposed facing of coursed brick haveemployed standard-sized brick, e.g. 3 /2 to 3% inches thick by about 8inches long. A very significant reason why such panels have not achievedsignificant market penetration is the predominating feeling amongmembers of bricklayer unions that industrialized mass production ofmodular panels incorporating bricks can curtail the amount of labor costfor fabrication of brick faced buildings and thus diminish theemployment and status of members of their unions. In fact, in certaininstances, the right of craft union members to boycott constructionsites utilizing prefabricated assemblies which could be fabricated onthe job has been judicially upheld. The present invention seeks to avoidthis problem by providing brick slabs so thin that they cannot normallybe set by hand under field conditions since they are no more than aboutone inch thick and therefore can normally only be set in industriallyprefabricated panels.

Brick are normally produced by extruding a column of green, plasticbrick material, then severing it into individual green brick for dryingand firing.

Accordingly, an obvious way to make brick slabs of one inch thicknessand less, would be to stretch wires across the mouth of the die fromwhich a brick column issues, thereby slicing individual brick up intothree to seven brick slabs that thus could be held to any desired beddepth from /8 to l".

So-called brick slabs have been made for many, many years. Sidingcontractors for years covered old buildings with brick slabs that wereheld in place with steel clips that were nailed to existing outsidewalls and which governed the arrangement of the brick facings. Mortarwas then tubed or tucked into the open joints. Of late years, there havebeen some sales of slabs to the do-it-yourself home owners. With some ofthe fine new adhesives on the market, it is not too difficult to glue ona very, very presentable brick facing that few would believe was only/2" thick.

To the best of the present inventors knowledge all slabs made to datehave been made by slicing with so-called outside wires. The job done bywires so placed produces an acceptable final product, but it isdifficult or impossible to knit the green slabs back into a single unitagainone that can be handled with ease in the normal manner that regularfull size brick are processed. The sliced-up brick slabs tend to fallapart, and each and every one of such brick slabs has to be handledvery, very carefully. If an outside face (only one per slabbed brick),is to be used, then perhaps every other course of brick being set on thekiln cars for future drying and firing has to be reversed, so that everybrick has its face in direct and full contact with the face of the brickit is setting on top of.

The latest and most modern brick plants which have mechanical settingmachines could not cope with the separation problems experienced withoutside wire brick column slicers.

The prior US. patents of others of which the inventor is aware include:

Converse et al., 551,306, wherein thin flat extrusions are provided withsmooth, kerfed, future break points. The process disclosed is believedto be impractical for production of clay brick slabs.

Atkins, 276,326, prevents laminations in an extruded product by using agrating prior to the forming die.

Chambers, Jr., 275,467, discloses production of a uniform column andapparatus for cutting the column into uniform-sized pieces.

Hilgendorf, 1,783,287, divides the product of a single cavity die intotwo totally separate issues which will have like surface finish on allfour sides. This is accomplished by first slicing the column, oiling thesame, then separating the two halves with another slicer that continuesto the face of the die.

Blom, 3,407,457, slices up a very fragile, non-plastic, uncured blockand tries to transport the same to an autoclave without damage.

Ullrich, 2,103,802 is concerned with transforming a multi-coveredextrusion into individual, hollow building brick through the use ofcutting wires and piercing wedges which cut and fold end portions ofhollow, rectangular extrusions into the equivalent of hollow brick.

Baer, 1,943,506 produces by extrusion plastic brick which have beenpresliced then pressed back together again suificiently tightly topermit their rough handling while still plastic, or when dried and/orburned without separating. Baers system involves oiling and anadditional shaper cap as well as wires which appear to be ditficult tozlelplgce and which are located in a non-tapering area of Stuckey,1,872,522 relates to the production of rocklike faces on concrete units.

Burch et al., 3,028,652 provides a system for slicing very tender andfragile material. No plastic mass is involved nor slicing of acontinuously extruded plastic mass.

Jacobsson et al., 3,065,514 like Blom and Burch relates to a process forslicing preformed tender and fragile block.

Reed, 2,230,309 kerfs extrusions so, after firing, indi vidual blocksmay be broken apart with smooth corners, but rough breaks.

SUMMARY OF THE INVENTION Bolted to the auger barrel of a brick extrudingmachine is an internal tapering die base to which is clamped an internaltapering shaper cap whose cross section upstream of its mouth isprovided with tensioned wires which slice the column longitudinally asit proceeds through said shaper cap. Downstream of the horizontal wires,the continued taper of the shaper cap forces into cohesion, bytremendous pressure, the adjacent longitudinal wire cut surfaces of theseverally created adjacent slabs, sufficiently enough to permit eachtransversely cut section, of the resulting multi-sectioned extrudedunit, to be safely manor machine-handled and to be processed through itssubsequent drying and firing cycles like normal full-size brick, unitsthat can at any time after firing be tapped apart on the original wirecut lines to create brick slabs, each e.g., to 1" thick, which areespecially economical and useful for facing the surfaces ofindustrialized mass-produced building panels of any practical size.

A particular means for tensioning and replacing the shaper cap wires isshown.

If the slicing wires are provided within the tapering shaper cap inaccordance with the present invention, instead of outside the same, theslabs will be pressed back together tightly enough to give a homogeneouslook and good physical handling ability to each multi-slab green brick,and yet leave a brick that can be easily tapped apart into itsconstituent slabs after burning.

In the preferred embodiment, the combination of a die base and shapercap interior rather sharply tapers in all its length. It is thisconstant interior size reduction that helps compact the moistened clayinto a slug that is very strong and smooth even though it is in aplastic state. The total pressure created from all exterior faces of theslug as it moves away from the slicing wires does the trick.

Not only will inside wires prove immensely helpful in making straight,thin facing slabs, but they can be just as beneficial in the manufactureof simple brick shapes which have all straight exterior lines.

All slabs and plain shapes have always commanded premium pricesfrom twoto five times as much per ton as compared with regular brick. There canbe produced when using the present invention just as many tons of slabsand plain shapes as of regular brick. Slabs and shapes can thus be very,very profitable items if, of course, any sizable sales can be generated.

The principles of the invention will be further hereinafter discussedwith reference to the drawing wherein a preferred embodiment is shown.The specifics illustrated in the drawing are intended to exemplify,rather than limit, aspects of the invention as defined in the claims.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a longitudinal, verticalcross-sectional view through a brick forming die having its taperingshaper cap provided with inside wires in accordance with the presentinvention;

FIG. 2 is a front end view of the forming die of FIG. 1;

FIG. 3 is a bottom plan view of the forming die, illustrating thepreferred means for holding the wires taut;

FIG. 4a is an elevat onal View of a reconstituted brick after firing;and

4 FIG. 4b is an elevational view of the brick of FIG. 4a after it hasbeen tapped apart into individual slabs.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENT A fragment ofthe auger barrel of a conventional brick extrusion machine is shown at10 in FIG. 1. An example of such a machine is the No. 40, manufacturedby J. C. Steele & Sons of Statesville, NC. The auger barrel 10 isprovided with a port which communicates with a tapering die base 12bolted to the auger barrel at 13. A die or shaper cap 14 is secured tothe die base in order to determine the shape of the four outsidesurfaces of the brick column. The column issuing from the die istransversely severed into brick, i.e. along the vertical transverseplane containing the arrow 16, using a conventional cutter. An exampleof such a machine is the No. 18, manufactured by J. C. Steele & Sons ofStatesville, NC.

A typical composition of as-extruded clay brick column 1s:

A typical composition of an as-extruded shale brick column is:

Constituent: Weight percent Water 13 Shale (dry basis) 87 The above areexemplary and subject to much variation as will be understood by thoseof ordinary skill in the art of brick manufacture.

In the example depicted, the cross-sectional internal dimensions of theshaper cap 14 are 8 /8 x 4% inches at the upstream end of the shaper and8% x 3% inches at the downstream end of the shaper cap. In this sameexample, the longitudinal distance between the upstream and downstreamends of the shaper cap, measured along the longitudinal axis of theshaper cap is 4% inches.

At a location intermediate the ends thereof, for instance where itscross-sectional dimensions are 8% x 4 inches, the shaper cap is providedwith a plurality of taut, parallel wires 19 extending between the shortsides 20 of the interior of the shaper cap and parallel to the longsides 22 of the interior of the shaper cap.

The wires 19 extend through openings 24 provided in the short sides 20of the shaper cap. Two, axially spaced lugs 26 are mounted on theexterior of each short side 20 of the shaper cap. Each lug has a likearray of openings 28 therethrough for mounting nut 30 and bolt 32assemblies 34 between axially aligned pairs of openings 28 of lugs 26 onthe same short side 20 of shaper cap. Each bolt 32 is provided with atleast one diametrical opening 36 for receiving an end portion of a wire19. In this fashion, the central portions of the wires 19 are disposedwithin the central opening of the shaper cap and the end portionsproceed out through the short side wall openings 24, through respectivebolt openings 28 and wrap about respective bolts. Two nuts 30 tightenedagainst opposite sides of one respective lug lock each nut and boltassembly against undesired rotation and together with the similarlylocked nut and bolt assembly at the opposite end of each wire, maintainthe respective wires in taut condition. It should be apparent that thisarrangement makes the individual wires 19 easy to keep tight and toreplace when necessary. The wires 19 are preferably of 11 gauge steel.Each wire end is wrapped sufficiently about its respective bolt that itproceeds tangentially therefrom toward the shaper cap. This, togetherwith predetermination of the spacing of the bolt holes arrays 28,ensures that the wire central portions within the shaper cap divide thecentral opening of the shaper cap into several substantially congruentrectangular areas,

as seen from and along the central longitudinal axis of the shaper cap.

In use, a brick extruding mixture, such as those set forth above by wayof example, is extruded at an extruder barrel pressure of, e.g., 500psi. at a rate of, 5g, 5 to 20 cubic feet per minute through the shapercap where the brick column is sliced by the wires 19 into four slabcolumns. In passing through the remainder of the tapering shaper cap,the slab columns are reunited sufliciently to cause the compositeissuing from the downstream end of the shaper cap to appear and behandleable as if it were a conventional, unsliced brick column. Uponissuing from the shaper cap, the column is cut by conventional means, asaforesaid, into composite brick of desired face height. These compositebrick (i.e. each comprising four separate, reunited slabs) may bemechanically picked up and set in normal cubes on conventional kiln carswhich may be pulled into a drier and kiln in the normal manner.

In a conventional drying and firing operation, to which the compositebrick are subjected prior to being tapped apart into individual brickslabs, the composite green brick are typically subjected to thefollowing conditions: 30 hrs. in a dryer reaching a temperature of about300 F., and 42 hrs. in a kiln where the maximum temperature could varybetween 1800 F. and 2400" F., depending on the raw materials.

Even after conventional drying and firing, the composite brick show noreadily visible evidence of having been presliced and reunited, theylook like conventional brick. However, upon being tapped, the compositebrick B readily separates along the cutting planes of the wires 19, intofour uniform faced brick slabs in the instance of the example, eachmeasuring about 2% x 8 x M; inches.

It would be surprising if there is a single plant in the United Statestoday that is producing building brick with the extrusion, drying firingsystems and other equipment that were almost in universal use in 1930.In 1930 it was not too uncommon to have one production man on thepayroll for each 800 brick produced daily. Today some plants have butone production employee for each 3,200 brick produced daily. Not onlyhas labor productivity been increased up to 400%, but much of the reallaborious work has been either eliminated or made much easier.

The extrusion and pugging machines in common use in 1930 required aboutone-and-a-half horse power per thousand brick produced per day. Thebrick as extruded were extremely soft by todays standards. They did notneed to be very hard, and they were not. In those days freshly extrudedbrick were generally hacked onto socalled double decked dryer cars andthe maximum height of the set on either deck was usually four coursesthebottom courses of brick thus only had to be extruded stilf enough tosupport three other brick without being deformed (mashed down).

Todys extruders may be powered with as much as four horse power perthousand of daily production. The extruded brick have to be very stiif,because freshly extruded brick are generally set directly onto kiln carsand to a height of up to 21 courses, without materially deforming thebottom course units. The moisture content of freshly extruded brick hasdropped from about 14-17 percent to about 12 percent or less.

Drying time has been cut from as long as four days to as little as 15hours. Less initial moisture plus intense, high speed circulation of airat the right temperature and of the right humidity has made this up to84% reduction in drying time possible.

In 1930 the tremendous benefits derived from deairing of building brickraw materials, prior to their extrusion, had just been discovered.However, general use of deairing was still years away. Deairing any clayat any moisture level greatly increases its green strength and itspotential dry and burned strengths. Through deairing, green columnstrengths could be so drastically improved that extrusion moisturelevels could almost be universally lowered. Many materials that, bythemselves or in combination with others, were not sufiiciently plasticat any acceptable moisture level to permit undeaired extrusion becameusable and desirable overnight through the use of deairing.

Today, deairing is substantially universally used in this country andsubstantially all brick extrusion machines now made in this countryutilize the deairing process.

Changes in the processes for production of face brick in the U.S., havein turn greatly increased the problems encountered in preslicing andsufiiciently semi-rescaling a brick column, to permit its subsequentcutting, setting, drying, firing, cooling, packaging, shipping,unloading, storage and job placement as unseparated units, but at thesame time, said units being readily and cleanly separable at their usesite by either being gently tapped with a suitable hammer or withanother like presliced and semi-presealed unit.

All basic building brick raw materials when ground and screened orsimilarly prepared, whether they are derived from surface clay, deepmined clay or bank shale or combinations of same, when moistened andworked, attain variable states of plasticity-the greater the moistureaddition, within limits, and the more thorough the working," the moreformable (extrudable) and stickier" each becomes. Evan in low mounds, avery selected few materials when horizontally wire cut into layers mayimmediately semi-reseal themselves, just through the downward pressureof their own weight, back into a seemingly unitary mass. Most allmaterials, however, at an equal moisture level and after equal workingcannot even be semi-rescaled without pressures substantially greaterthan the force of gravity being exerted on same.

Todays nearly universal use of deairing extrusion machines and very hightunnel kiln car settings, have combined to eifect near common use ofvery hard, low moisture content green brick columns. Todays extrusionsare so hard and strong that they can be walked on or even jumped on withscarcely any resulting marks or deformations. Twenty-one green brick canbe piled on top of one another or cross set every other pair of coursesto an equal height, without any noticeable deformation of even thebottom unit taking place. In 1930 it took years to train and assemble ascrew of light enough fingered men to pick off and set green brickwithout marking same with finger pressures. When todays relatively dry,hard and low plasticity brick columns are presliced substantialpressures have to be exerted to effect satisfactory semi-reseals, justto permit the extrusion, cutting and setting operations to normallyproceed.

In some instances, brick units that have ben conventionally sliced, thensemi-rescaled sufiiciently to stay in one piece to permit placing on akiln car, will separate during todays extremely fast drying cycles. Upto onehalf of a green bricks total eventual shrinkage may occur duringdrying, and it is not uncommon for this alone to amount to (on an 8"brick). When several days were utilized to remove the mechanical water(i.e., the water not chemically combined) from green brick, the removalproceeded at such as slow pace that the differential shrinkage withineach unit was held to a minimum, the so-called interior slabs drying andshrinking very nearly at the same rate as the outside slabs (those withmore exterior surface exposure). When brick are dried in 15 hours it isjust about impossible with today's knowledge and equipment to preventdifierential shrinkage within individual pre-sliced and semi-rescaledunits-the mainly exterior slabs shrinking long before the mainlyinterior slabs do, to set up terrific strains on the semi-reseal lines.

The very fast firing cycles presently used also present a like problem.Generally,.over half a bricks total shrinkage occurs during its firing%"not being too uncommon for an 8" brick. Here again, outside slabs getheated up considerably ahead of inside slabs in the same unit.Differential shrinkage can exert terrific pressures on the semi-reseallines. Without sufiicient semi-resealing pressure, separations willoccur, and separations at this stage can result in very, very costlykiln wrecks ((brick makers jargon for a toppled kiln car). One separatedburned slab falling off the side of a car can start a pileup inside akiln that can cost up to $65,000 in lost production alone. In prioryears, with beehive stationary kiln operations, fall oifs of this typewere inconsequential, the usual direct loss being at most the value ofeach fall olf slab.

Semi-rescaled units that have withstood internal and external strainsthrough extrusion, cutting, hacking, drying and burning face yet anothertest of their semi-reseals. Current very fast cooling cycles, 2,000 F.down to 250 F. in as little as seven hours, for instance, createadditional differential shrinkage strains, and I suspect, resealfailures. Here again, failures can produce fall offs, and fall offs, inturn, can cause very costly kiln wrecks.

Yet another straw exists to break our camels back. Cubing of burnt brickfor fork lift handling, being practiced with increasing incidence, isvery rough on individual brick units. Bottom brick adjacent to forkholes get rapped, poked and shoved. Air powered steel strappingtighteners and sealers exert point strains that can snap first qualityunsliced brick. The careful manhandling and final nest of straw that useto feather-bed brick in transit are virtually no longer used.

Obviously, if one is going to make a success of manufacturing brick slabunits, his method of producing semireseals has got to be positive, nearfoolproof and just as satisfactory to the buyer as it has been to makeby the manufacturer. All former preslicing and semi-resealing systemsthat I know of cannot be used satisfactorily today. What one could getby with forty, thirty, twenty, or ten years ago under some or mostcircumstances will not work today. Every segment of brick manufacturehas radically changed, and every such change has made semiresealing ofpresliced planes more and more difiicult. A new and diiferent method ofobtaining satisfactory semiresealing was needed at the time my inventionthereof was made.

I personally have tried to use spot oil lubrication on dry dies (diesthat are normally not equipped with any means of lubrication) and havebeen my industry friends do the same. I have never seen spot oiling usedsuccessfully, that is without constant adjusting being required andfrequent very out of balance extrusions being made, extrusions that hadto be scrapped. Trying to balance a die by using a slicker" and spotlubrication is like locking the barn door after the horse has beenstolen-it is too late. One may be able to make an improved appearingcolumn, but the column Weaknesses remain.

Vast tonnages of clay, shale or mixtures thereof are being extrudedtoday, and have been historically, without the use of any lubricant inany way. Sewer piper, flue lining, hollow tile, hot tops, drain tile,and the like, have historically been extruded through so-called drydies, which are non-lubricated for very good reasons.

Lubricants are basically used to reduce the friction that is built upwhen plastic clays are forced at very high pressures against and alongmetallic enclosures such as the interior surfaces of die bases andshaper caps. The need to reduce this friction is dictated by the need tobalance the flow of clay out of a die, a balanced flow being achievedwhen all cross-sectional areas of a clay column emerge from a shaper capat the same speed and in a truly cohesive mass. In normal brickextrusion, without effective lubrication, the center of the column willrun very fast, and when this happens, so-called laminations willdevelop. Lamination lines are the result of adjacent bodies of claytravelling at dilferent rates of speed, actually losing homogeneity,really becoming separate entities that are pressed tightly togethersotightly that the extruded column appears to be homogeneous to the eye,can be cut into desired lengths with no problem and then be man-handledand stacked for drying. Ware cut from a seriously laminated columngenerally is unable to stand the strains and stresses encountered indrying and/or firing. One ends up with actual pieces, badly crackedunits, deformed units (crooked-twisted), or units that cannot passrequired strength tests; scrap, to be exact.

Generally speaking, exterior column lubrication, inside a die base andshaper cap, for example, is required when a sizable mass such as a brickbody, solid or cored, is to be extruded. The exterior frictional drag,without lubrication being employed, simply becomes greater than theclay-to-clay bonding strength, and the center area breaks away and takes01f on its own. The separation caused by different interior columnspeeds can actually result in multiple concentric rings (lamellae) ofmaterial, each of which are travelling at their own rate of speed andforming adjacent slicked surfaces in the process. It is these slickedsurface parting lines that later give way when the body is subjected torapid differential temperature changes.

To obtain the maximum benefit from any lubricating medium, it isnecessary that effective lubrication start at the point where the claymass being forced out of the augers starts to enter a reducedcross-sectional area. No application of lubrication at or near the tailend of the forming process can possibly mend previously formedlamination lines. The lubricated slicker of Baer 1,943,506 obviouslycould merely contain the sliced-up column long enough to have it extrudein a straight, horizontal line and achieve a very minimal amount ofresealing through the build up of back pressure.

Now, when one extrudes relatively thin walled products, such as fluelining, sewer pipe and the like, the situation is entirely different.With such products the plastic material is forced between two closelyspaced metal surfaces which results in a near equal frictional drag onboth surfaces. This double, near equal drag, on relatively smallcross-sections, rarely produces harmful laminations. The section is justtoo narrow and under too much equalized forward thrust to permit arelatively tiny center area to break loose and travel at a diflEerentspeed from its adja cent sides. Dry dies have always had theirapplication in such production and probably always will, so long as suchproducts are manufactured.

To properly lubricate, with total coverage, the interior of a die baseand its attached shaper cap, todays most popular lubrication systemintroduces its oil at the rear of the die base through a continuousencircling totally machined slit equivalent which employs an overhanginglip to provide clearance for oil introduction and to prevent plugging ofthe slit by clay. Oil is fed to this oiling ring by several spacedflexible hose lines in order to insure equal pressure at all points.These multiple lines all are generally fed from a common source andcontrolled by a single valve. Pressures of up to 300 psi. are employed.Pressures are varied slightly from day to day to suit different coringset ups, different textures, and the like. Once the lubricant is set forany specific set of conditions, it is not uncommon for a full days runto be made without further adjustments being called for, and nearperfect protection is afforded against the formation of damaginglaminations.

A propertly lubricated column, of course, requires less powerexpenditures than a non-lubricated column, but the power saving isincidental and not the primary reason for supplying lubrication. Baersrescaling was not and could not have been sufficient to work with todayslow moisture content brick columns, very high green brick settingpatterns, and fast drying, firing and cooling schedules, and that thedifferences between his method and mine, as disclosed, are material.

Recent tests A series of tests have been conducted under my directionand at my request at K.F. Brick Co. of South Windsor, Conn., utilizingtapered shaper caps constructed in accordance with the principles of theinvention.

In a first test the die shaper cap used was configured as depicted inthe figures of this application, except that four slicing Wires wereinstalled with equal spacing across the shaper cap to produce fiveslabs. The so-called brick column started emerging in the normal manner,and individual brick cut from said column were quite normal, being inone piece and very difiicult to separate on the presliced lines. In avery short time, however, actual separations on one of the preslicedlines was noticed, and the run 'was terminated forthwith.

Once the shaper cap assembly had been removed and cleaned out, the causeof the trouble was readily apparent. Someone had made a mistake insetting up the slicing assembly, by cutting the piano wire slicing wirestoo short-not long enough to permit the customary number of holdingwraps around the exterior of the tightening posts. The lack of thenormal number of wraps allowed a slippage to occur, resulting in apronounced bowing of the piano wire slicing wires in the downstreamdirection of the clay column flow.

Each of the wires had slipped a different amount, but none of them hadbowed as much as one-half its proper distance from the exit end of theshaper cap assembly, the wire with the greatest slippage justapproaching the half-way mark. The location of the wire with thegreatest slippage, as could be expected, matched up with the brickcolumn separation that was discovered shortly after the run was started.Had the run been continued a 'bit longer, the other slicing wires wouldhave no doubt shortly stretched enough to have caused column separationsat their individual planes.

On this particular very short run of slabbed brick units at K.F., theunits extruded and cut prior to the start of column separations werehacked onto kiln cars in the normal manner and subsequently dried andfired in the usual way. After firing it was found that many of the firedunits had separations that did not exist when they were put on the kilncars (individually by hand). Also, it was found that several units thathad been fiat or edge set on the outsides or ends of the cars wereactually missing one or more slabs, said slabs having obviouslyseparated during the firing or cooling processes. All cars were visuallyinspected-both ends and both sidesafter going through the dryer andprior to going into the kiln and having fallen off in the kiln. Mostfortunately, the slabs that did drop off just happened to fall and landso as not to jam a bottom course of brick and result ina kiln wreck; aforerunner, usually, of several toppled cars, as the spaced bricksettings react very much like a row. of dominosa chain reaction thatusually is not dissolved until the hydraulic car pusher pressureincrease either sets off, an alarm or shuts down the pusher.

I have seen as many as fifteen adjacent cars of brick all toppled in onebig mess up against the inside walls of a kiln, with portions of'tha'tkiln at 2,000 F.

A kiln wreckis always a very expensive accident" and can becatastrophically so. They always completely shut down production, causethe lay off of as many as 90% of the plant labor "force, and onrestartup, generally entail a considerable production of off-color ware.It can take as long 'as'three days to cool a kiln down sufficiently toallow workmen to enter it and clean out a wreck. Interior kiln damagecaused by a bad wreck can take up two around-the-clock days to repair.Getting a kiln 'back up to temperature generally takes a minimum of fourdays. At the K.F. plant where the run of presliced brick was made, thekiln puts out 130,000 brick per daybrick that have a wholesale value of$50.00 per thousand. A serious kiln wreck can and has cost K.F. as muchas $65,000.00 in lost production alone. Kiln wrecks are obviously a veryserious matter. One cannot afford to take chances. Any presliced brickthat K.F. or anyone else runs has to be near foolproof. One can restassured, they will not permit the use of short wires at K.F. again.

The accident at K.F. certainly would seem to prove my contention thatonly a tapered die can semi-reseal a wire-cut plastic brick columnsufficiently to permit modern handling, drying and firing of every brickcut from same. No company can aflford or would take chances of puttingpresliced semi-rescaled brick through a tunnel kiln if they were notpositive that of the individual brick would remain in one place.

Specifically, this lapse in properly preparing a preslicing andsemi-rescaling shaper cap for production proved:

(1) Even a tapered die section, located after the slicing wires, has tohave a minimum length to eifect a satisfactory semi-reseal of wire cutcolumn sections-a semi-reseal sufficiently good to permit 100%effectiveness through manual or mechanical setting operations, kiln cardrying, tunnel kiln firing and cooling, hand or mechanical packaging,subsequent rail car or truck ship ment and the final receiving, storing,and in plant movement at the precast plant where the units will finallybe tapped apart and the individual slabs used to face precast panels.

(2) Even a column of presliced brick units that have been semi-rescaledsufficiently to permit high speed cutting into brick units, very roughmanual or mechanical setting on kiln cars and almost instantaneousstacking up to twenty-one courses high without deformation or separationmay not be semi-rescaled good enough to stand today's very rapid drying,firing and cooling cycles which generate very fast and uneven expansionand contractionsthe expansions and contractions that split up suchsemi-rescaled brick slab units at K.F. Brick Co. and nearly caused avery serious kiln wreck.

(3) That 1930 semi-rescaling processes could hardly be expected to besatisfactory today; not one person I know of ever made use of acontinuous tapered die section after slicing wires to semi-preseal apresliced unit, and I seriously doubt that an untapered die sectioncould ever exert the pressure that a tapered section can and that even asubstantial length of a tapered die section is needed, as a brief lengthof tapered section cannot reseal presliced brick sufficiently to evenmake a satisfactory brick column out of the certain deaired, very lowmoisture content raw material as used at K.F. Brick Co. at South WindsorHill, Conn.

For a second test, four slicing wires were in place, giving variousdepth locations in the shaper cap, from a minimum of to a maximum of 3%.

First we ran a soft column above normal moisture content. The column ranand cut fine with no sign of any separations. This column was aboutequal in moisture content to what was commonly run in 1930. The cutbrick were hackable about three courses high without seriousdeformation, but no higher. At this plant the normal set is 21 courseshigh. None of these unusable brick were saved for moisture contentdetermination, drying or firing.

At the next stage of this test run, the moisture content of the clay andshale mix being extruded was cut back to what is presently normal.Immediately there was a complete separation of the column as it emergedfrom the mouth of the shaper cap at the presliced line from wire A whichwas only inside the shaper cap some 4". Furthermore, while the resea onthe line out 1 1 by wire C (inside the shaper cap 1%") was good enoughto prevent separation through issuance, cutting, transporting andsetting, it was not good enough to allow it to go on a car into thedryer and kiln. Freshly cut brick could too easily be pulled apart onsaid line C.

The reseals experienced at lines E and G (back in the shaper cap 2 /2"and 3%", respectively) on this part of the test were normal, offeringreal resistance to forcible separation by hand.

I do not know any practical way to measure the tremendous resealingpressures that we obtain with interior preslicing in a tapered shapercap section, but I am sure that they have to be many, many times thatwhich could be attained with Baers system, which utilizes a straightsectioned containment after slicing. There was even a very noticeabledifference in the texture of the four sets of facings produced with thissetup, going from a comparatively coarse finish from wire A to a veryfine finish from wire G. I feel sure we attained substantially moreresealing pressure after wire A than Baer did with any of his wires.Certainly, all evidence available to me indicates this to be so.

During a third test, all eight wire stations were in use- A, B, C, D, E,F, G and H.

Again, on this test run, we started out with a relatively soft columnbut not nearly as soft as during our first run with this shaper cap oras soft as was run in most plants in 1930. We experienced some immediateminor reseal failures at line A, but some obviously were a result of thebit stiffer (dryer) clay mass being extruded than on previous test runs.The reseals on all the other lines appeared to 'be satisfactory.Forty-eight samples were boxed in (to prevent any possible fall off) ontop of a kiln car set and on one which was run through the dryer in theregular manner. Three samples were also saved to be tested for watercontent.

Twenty-four samples were removed after the car came out of the dryer(before it was put in the kiln). Thirteen samples came out whole; 1brick had a partial separation on line A; and had total separations online A. The fidgeg moisture content on the three samples averaged Wefollowed the same procedure with another test run using a presentlynormal moisture content mix. Again, we experienced separation problemswith line A. Again, we put 48 good samples on top of a kiln car and sentthem through the dryer, as well as saving three samples for moisturedeterminations. Nine of the 25 removed from this set came out whole,three were separated on line A and 13 had separated on line B. Thisshift in predominance of separations from line A to line B I believe tohave been due to differential flow at that exact point. The preslicingat that weak" point just set it free. The fact that we had no trouble atthe B point on previous normal consistency runs, when there was no wirethere, and had never encountered any separation problems, at any point,in the bottom half of the brick column, which had been presliced bywires at E, F, G and H, all of which were better than half-way back inthe shaper cap, I believe overwhelminingly substantiates this deduction.It is a well recognized fact, that with solid brick extrusions (notcored), the best lubrication systems and the most efficient de-airing,in combination, do not eliminate the extra center push that developsinside a die base and shaper cap. The natural stickiness of clay, and/orshale, with a good lubrication system and efiicient de-airing do notprevent harmful laminations from occurring. A preslicing wire at theright spot, and not far enough into the shaper cap to receive subsequentsuflicient resealing pressure, leaves a slicked former separation thatwill give way when subjected to the strains set up by fast drying,burning and cooling. The drier the mix, the greater the problem ofdifferential flow, and the more ditficult it is to reseal a preslicedcolumn. No separation problems were experienced at any process pointthrough drying, at

any moisture level, at presliced lines C, D, E, F, G and H. This isevidence that not only is slicing in a tapered section needed, but thatthe slicing wires have to be well back in tapered section if sufiicientresealing pressures are to be appliedsufficient resealing pressures toinsure positive protection from any separation at any point. The addedmoisture content on the three samples taken from this run average out at12.51%

Ten of first brick made in this test, brick that averaged 13.8% addedmoisture, which came out of the dryer whole, were put on another kilncar and sent through the kiln. All of these brick survived the fastfiring and fast cooling. While the slabs separated by wires A and Bcould generally be tapped free with no trouble, the slabs presliced bywires D, E, F, G and H could not be successfully tapped apart-they hadbeen too effectively resealed-too much pressure had been applied on toosoft, too plastic, too sticky and too wet a body. Had this body been assoft as most 1930 columns, it is very doubtful if even the B line couldhave been easily tapped apart.

The nine whole 12.51% brick that survived their trip through the dryerwere put on a kiln car (the same one as the 13.8% brick) and sentthrough the kiln. Three of these suffered separations on A or B, orboth, from fast firing or fast cooling or a combination of same. Thebalance were too tight on lines D, E, F, G and H-tOok too much tappingto separate and the losses were too high. I would like to point out thatthe just described so-called cold tests, as were these short test runs,will vary in results that one will get from real production runs. Coldtests in general use a very high percentage of re-run raw material, andthe material extruded is relatively cool as are the extrusion machinesaugers, auger barrel die base and shaper cap. One can generally expectand get much more effective reseals with like slicing wire placementwith cold runs than one can with hot production runs. In our normalproduction runs to date, we have had all slicing wires the same distancefrom the mouth of the shaper cap, in about 2%", which by itself makesfor an extra squeeze. We have had only very minor problems in separatingslabs for use and practically no separation problems during manufacture,packaging, etc.

Suitable die bases and shaper caps are available from J. C. Steele &Sons, Statesville, N.C. A suitable shaper cap is e.g. 4.25 inches longand has an internal taper of 2-4 degrees, more preferably 2.5-3.25degrees. With cold runs, I have found that wires placed 0.75-0.1875 inchback in the shaper cap dependably give insufiicient resealing when stiffbrick columns were extruded, e.g. of commercially significant moisturecontent. Likewise, I have found that wires placed more than 2 inchesback produced over-resealed Ware in cold runs. However, in hot runs,i.e. sustained production, 1.75-2.00 inches appear to be an optimumset-back for the wires (measured from the small end of the shaper cap).Thus, for overall use and including a sufficient range to accommodateboth hot and cold runs, and extrusions both somewhat wetter and somewhatdrier than commercially optimum, a range of 1375-225 inches setback ofthe slicing wires from the small end of the shaper cap is suggested.

It should now be apparent that the improved method for making facedbrick slabs as described hereinabove possesses each of the attributesset forth in the specification under the heading Summary of theInvention hereinbefore. Because the method for making faced brick slabsof the invention can be modified to some extent without departing fromthe principles of the invention as they have been outlined and explainedin this specification, the present. invention should be understood asencompassing all such modifications as are within the spirit and scopeof the following claims.

What is claimed is:

1. An improved method for making brick slabs comprising: extruding acolumn of green brick through a tapering die which has a taper in therange of 2-4 degrees; intermediate the tapering die between 1% and 2%inches from the smaller end thereof, continuously slicing the brickcolumn into a plurality of slab columns; and utilizing the taper of thedie downstream of performance of the slicing step to pressingly reunitesaid plurality of slab columns into an apparently unitary, compositebrick column; cutting the apparently unitary, composite brick columninto a plurality of apparently unitary, composite green brick ofpreselected face height; drying and firing said apparently unitary,composite green brick; and tapping the dried and fired apparentlyunitary, composite brick apart into a plurality of individual bricksla'bs along the line(s) of slicing of said column of green brick.

2. The improved method of claim 1 wherein said green brick column ismore than three inches thick and wherein each brick slab is no more thanone inch thick.

3. The improved method of claim 2 wherein said green brick column isessentially composed of clay and water.

4. The improved method of claim 2 wherein said green brick column isessentially composed of ground shale and water.

5. An improved method for making brick slabs comprising: extruding acolumn of green brick through a path of continuously decreasingcross-sectional area of 24 degrees taper; stationing at least one tautwire crosswise of the path of the column of green brick intermediate theextruding step within 1%-2% inches of the downstream end of said pathand slicing said column with said at least one taut wire into aplurality of slab columns; downstream of the slicing step, squeezing theslab columns mutually toward one another into an apparently reunitedcolumn of green brick; cutting the apparently united column of greenbrick into a plurality of apparently unitary composite green brick ofpreselected face height; drying and firing said apparently unitary,composite green brick; and tapping the dried and fired apparentlyunitary, composite brick apart into a plurality of individual brickslabs along the line(s) of slicing of said column of green brick.

6. Apparatus for use with a brick column extrusion machine in theproduction of brick slabs comprising:

a tubular, tapering die of generally rectangular internal transversecross-sectional shape;

at least one brick column slicer mounted on said die in such orientationas to divide the interior of said die into at least two laterallyadjacent regions of generally rectangular transverse cross-sectionalshape, said at least one brick column slicer being mounted axiallyintermediate the tapering die; whereby green brick being extruded in acolumn through said die is sliced by said at least one slicer into atleast two laterally adjacent slab columns and pressed by the continuingtaper of the die into an apparently reunited composite column of greenbrick; said die having a taper in the range of 24 degrees and said atleast one slicer being set back 1%2% inches from the smaller end of thedie.

7. The apparatus of claim 6 wherein the at least one brick column slicercomprises three, parallel, equally laterally spaced slicing wires andwherein said tubular, tapering dies is of such internal size and shapeas to produce a composite column substantially equal in green bricklength and green brick thickness to a conventional green brick column.

8. The apparatus of claim 7 further comprising means defining openingsin said die for passing opposite end portions of said slicing wires tothe exterior of said tapering die; and means mounted on the exterior ofsaid die for tautening and securing the opposite end portions of saidslicing wires.

9. The apparatus of claim 8 wherein said tautening and securing meanscomprise two pairs of axially spaced lugs mounted opposite one anotheron the exterior of said tapering die; means defining three pairs ofaxially aligned openings through each pair of axially spaced lugs; a nutand bolt assembly received through and mounted on each pair of axiallyaligned openings; the end portions of each slicing wire being secured torespective of said nut and bolt assemblies.

References Cited UNITED STATES PATENTS 287,699 10/1883 Meeker 264146854,823 5/ 1907 lHedrich 26467 1,245,898 11/1917 Gates 425467 1,920,9828/ 1933 Hedrich 2645 8 1,943,506 1/ 1934 B-aer 42597 2,209,643 7/ 1940Chamblin 264152 FOREIGN PATENTS 269,761 4/ 1927 Great Britain.

JOHN H. MILLER, Primary Examiner US. Cl. X.R.

